Preservation solutions modulate hydrogen sulfide synthesis in saphenous vein endothelium during coronary artery bypass grafting
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Background
The saphenous vein (SV) remains the most widely used graft in coronary artery bypass grafting (CABG). However, graft failure over the years has compromised long-term outcomes. Preservation of the vascular endothelium is fundamental for vein graft patency, and hydrogen sulfide (H 2 S) a protective gasotransmitter, plays a significant role in vascular homeostasis. This study evaluated how different intraoperative preservation solutions modulate H 2 S-synthesizing enzymes and endothelial integrity.
Methods
SV segments from 20 CABG patients were subdivided into five groups: Control (immediate fixation), normal saline (NS; 0.9% NaCl), autologous heparinized arterial blood (AHB), histidine-tryptophan-ketoglutarate (HTK) solution, and a damage group (no solution for 30 minutes). Structural integrity was evaluated by measuring endothelial coverage using light microscopy, and the expression of eNOS, CD31, and H 2 S pathway enzymes (CSE, CBS, and 3-MPST) was assessed by immunofluorescence (IF) and confocal microscopy to determine mean fluorescence intensity (MFI).
Results
LM analysis revealed that AHB (89.66% ± 3.02) and HTK (88.72% ± 3.07) preserved endothelial coverage significantly better than NS (78.06% ± 4.48) and the Damage Group (76.82% ± 4.90; p < 0.001). In IF, all interventions reduced eNOS and CD31 expression compared to the control, but AHB and HTK maintained significantly higher levels than NS (p < 0.001). All three H 2 S-producing enzymes were detected in the GSV endothelium, with CSE being the most expressed isoform. The use of NS caused a marked depletion of these enzymes, while AHB and HTK showed specific superiority in preserving H 2 S synthesizing enzymes.
Conclusions
The choice of preservation solution significantly affects endothelial integrity and the modulation of enzymatic H 2 S synthesis. NS proved to be deleterious to the endothelium, whereas AHB and HTK better preserved vascular structure and function, suggesting their clinical superiority for the preparation of venous grafts during CABG.
Clinical Perspective
What Is New?
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This study confirms the presence of the three primary hydrogen sulfide (H 2 S)-synthesizing enzymes—cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MPST)—in the human saphenous vein (SV) endothelium.
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It demonstrates that the use of normal saline (0.9% NaCl) as a storage solution for vein grafts—a common practice in many surgical centers—promotes a considerable reduction in the expression of H 2 S and nitric oxide (NO)-producing enzymes and negatively impacts the physical integrity of the endothelium.
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HTK solution and autologous blood preserve not only the endothelial structure but also the production of essential gasotransmitters, specifically and NO, within the vein graft.
What Are the Clinical Implications?
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The proper choice of intraoperative preservation solution should be standardized to avoid the use of normal saline, aiming to minimize initial endothelial dysfunction.
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Maintaining H 2 S expression using buffered solutions or autologous blood may be a noteworthy strategy to preserve the SV endothelium during coronary artery bypass grafting (CABG).
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Preserving these gasotransmitter pathways can mitigate intimal hyperplasia and accelerated atherosclerosis, ultimately improving long-term vein graft patency and clinical outcomes for patients
